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Lombard effect
thumb|250 px|Due to the Lombard effect, [[Great tits sing at a higher frequency in noise polluted urban surroundings than quieter ones to help overcome the auditory masking that would otherwise impair other birds hearing their song. In humans, the Lombard effect results in speakers adjusting not only frequency but also the intensity and rate of pronouncing word syllables.Slabbekoorn H, Peet M. (2003). Birds sing at a higher pitch in urban noise. Nature. 424(6946):267. ]] The Lombard effect or Lombard reflex is the involuntary tendency of speakers to increase the intensity of their voice when speaking in loud noise to enhance its audibility.Lane H, Tranel B. (1971). The Lombard sign and the role of hearing in speech. J Speech Hear Res 14:677-709. abstract This change includes not only loudness but also other acoustic features such as pitch and rate and duration of sound syllables.Junqua JC. (1993). The Lombard reflex and its role on human listeners and automatic speech recognizers. J Acoust Soc Am. Jan;93(1):510-24. Summers WV, Pisoni DB, Bernacki RH, Pedlow RI, Stokes MA. (1988). Effects of noise on speech production: acoustic and perceptual analyses. J Acoust Soc Am. 84(3):917-28. This compensation effect results in an increase in the auditory signal-to-noise ratio of the speaker’s spoken words. The effect links to the needs of effective communication as there is a reduced effect when words are repeated or lists are read where communication intelligibility is not important. Since the effect is also involuntary it is used as a means to detect malingering in those simulating hearing loss. Research upon Great tits and Beluga whalesScheifele PM, Andrew S, Cooper RA, Darre M, Musiek FE, Max L. (2005). St. Lawrence River beluga Indication of a Lombard vocal response in the St. Lawrence River Beluga. J Acoust Soc Am. 117(3 Pt 1):1486-92. that live in environments with noise pollution finds that the effect also occurs in the vocalizations of nonhuman animals. The effect was discovered in 1909 by Étienne Lombard, a French otolaryngologist.É. Lombard (1911), "Le signe de l'élévation de la voix", Annales des Maladies de L’Oreille et du Larynx, Vol. XXXVII, No. 2, pp. 101–119. Lombard speech When heard with noise, listeners hear speech recorded in noise better compared to that speech which has been recorded in quiet and then played given with the same level of masking noise. Changes between normal and Lombard speech include: * increase in phonetic fundamental frequencies * shift in energy from low frequency bands to middle or high bands, * increase in sound intensity, * increase in vowel duration, * spectral tilting, * shift in formant center frequencies for F1 (mainly) and F2. * the duration of content words are prolonged to a greater degree in noise than function words.Patel R, Schell KW. (2008). The influence of linguistic content on the Lombard effect. J Speech Lang Hear Res. 51(1):209-20. * great lung volumes are used,Winkworth AL, Davis PJ. (1997). Speech breathing and the Lombard effect. J Speech Lang Hear Res. 40(1):159-69. PMID 9113867 * it is accompanied by larger facial movements but these do not aid as much as its sound changes. Vatikiotis-Bateson E, Chung V, Lutz K, Mirante N, Otten J, Tan J. (2006) Auditory, but perhaps not visual, processing of Lombard speech. J. Acoust. Soc. Am. 119: 3444. abstract These changes cannot be controlled by instructing a person to speak as they would in silence, though people can learn control with feedback.Pick HL Jr, Siegel GM, Fox PW, Garber SR, Kearney JK. (1989). Inhibiting the Lombard effect. J Acoust Soc Am. 85(2):894-900. The Lombard effect also occurs following laryngectomy when people following speech therapy talk with esophageal speech.Zeine L, Brandt JF. (1988). The Lombard effect on alaryngeal speech. J Commun Disord. 21(5):373-83. Mechanisms The intelligibility of an individual’s own vocalization can be adjusted with audio-vocal reflexes using their own hearing (private loop), or it can be adjusted indirectly in terms of how well listener’s can hear the vocalization (public loop). Both processes are involved in the Lombard effect. Private loop A speaker can regulate their vocalizations particularly its amplitude relative to background noise with reflexive auditory feedback. Such auditory feedback is known to maintain the production of vocalization since deafness effects the vocal acoustics of both humansWaldstein RS. (1990). Effects of postlingual deafness on speech production: implications for the role of auditory feedback. J Acoust Soc Am. 88(5):2099-114. and songbirdsKonishi M. (1965). Effects of deafening on song development in American robins and black-headed grosbeaks. Z Tierpsychol. 22(5):584-99. Changing the auditory feedback also changes vocalization in human speechSiegel GM, Schork EJ Jr, Pick HL Jr, Garber SR. (1982). Parameters of auditory feedback. J Speech Hear Res. 25(3):473-5. or bird songLeonardo A, Konishi M. (1999). Decrystallization of adult birdsong by perturbation of auditory feedback. Nature. 399(6735):466-70. . Neural circuits have been found in the brainstem that enable such reflex adjustment.Hage SR, Jürgens U, Ehret G. (2006). Audio-vocal interaction in the pontine brainstem during self-initiated vocalization in the squirrel monkey. Eur J Neurosci. 23(12):3297-308. Public loop A speaker can regulate their vocalizations at higher cognitive level in terms of observing its consequences on their audience’s ability to hear it. In this auditory self-monitoring adjusts vocalizations in terms of learnt associations of what features of their vocalization, when made in noise, create effective and efficient communication. The Lombard effect has been found to be greatest upon those words that are important to the listener to understand a speaker suggesting such cognitive effects are important. Development Both private and public loop processes exist in children. There is a development shift however from the Lombard effect being linked to acoustic self-monitoring in young children to the adjustment of vocalizations to aid its intelligibility for others in adults.Amazi DK, Garber SR. (1982). The Lombard sign as a function of age and task. J Speech Hear Res. 25(4):581-5. Neurology The Lombard effect depends upon audio-vocal neurons in the periolivary region of the superior olivary complex and the adjacent pontine reticular formation. It has been suggested that the Lombard effect might also involve the higher cortical areas that control these lower brainstem areas.Jürgens U. (2009). The neural control of vocalization in mammals: a review. J Voice. Jan;23(1):1-10. Choral singing Choral singers experience reduced feedback due to the sound of other singers upon their own voice.Tonkinson S. (1994). The Lombard effect in choral singing. J Voice. 8(1):24-9. This results in a tendency for people in choruses to sing at a louder level if it is not controlled by a conductor. Trained soloists can control this effect but it has been suggested that after a concert they might speak more loudly in noisy surrounding as in after-concert parties. The Lombard effect also occurs to those playing instruments such as the guitarJohnson CI, Pick HL Jr, Garber SR, Siegel GM. (1978). Intensity of guitar playing as a function of auditory feedback. J Acoust Soc Am. Jun;63(6):1930. Animal vocalization Noise has been found to effect the vocalizations of animals that vocalize against a background of human noise pollution. Great tits in Leiden sing with a higher frequency than do those in quieter area to overcome the masking effect of the low frequency background noise pollution of cities. Beluga whales in the St. Lawrence River estuary adjust their whale song so it can be heard against shipping noise Experimentally, the Lombard effect has also been found in the vocalization of: * BudgerigarsManabe K, Sadr EI, Dooling RJ. (1998). Control of vocal intensity in budgerigars (Melopsittacus undulatus): differential reinforcement of vocal intensity and the Lombard effect. J Acoust Soc Am. 103(2):1190-8. * Cats Nonaka S, Takahashi R, Enomoto K, Katada A, Unno T. (1997). Lombard reflex during PAG-induced vocalization in decerebrate cats. Neurosci Res. 29(4):283-9. * Common marmosetsBrumm H, Voss K, Köllmer I, Todt D. (2004). Acoustic communication in noise: regulation of call characteristics in a New World monkey. J Exp Biol. 207(Pt 3):443-8. * Cottontop tamarinsEgnor SE, Hauser MD. (2006). Noise-induced vocal modulation in cotton-top tamarins (Saguinus oedipus). Am J Primatol. 68(12):1183-90. * Japanese quailPotash LM. (1972). Noise-induced changes in calls of the Japanese quail. Psychonomic Science, 26, 252–254. * NightingalesBrumm H. (2004). An Acad Bras Cienc. Causes and consequences of song amplitude adjustment in a territorial bird: a case study in nightingales. 76(2):289-95. * Rhesus MacaquesSinnott JM, Stebbins WC, Moody DB. (1975). Regulation of voice amplitude by the monkey. J Acoust Soc Am. 58(2):412-4. * Squirrel monkey. * Zebra finchesCynx J, Lewis R, Tavel B, Tse H. (1998). Amplitude regulation of vocalizations in noise by a songbird, Taeniopygia guttata. Anim Behav. 56(1):107-13. See also *Auditory masking *Bird vocalization *Human Voice *Intelligibility (communication) *Loudness *Noise health effects *Noise pollution *Speech *Whale song References Category:Phonetics Category:Human voice Category:Animal communication Category:Human communication Category:Noise pollution pl:Efekt Lombarda